ABSTRACT
Manufacturing process of gear is fairly complicated due to the presence of various simultaneous motions of the cutter and the job. In this paper, an attempt is made to generate meaningful design data for a spur gear and the corresponding rack form cutter necessary for the manufacturing process. Using these information, solid models for the cutter and blank are developed and finally gear-manufacturing process is simulated in a virtual manufacturing environment. The user can switch between design and manufacture mode at will. The integrated process may also help to develop an optimized product. For better understanding of the operational principle, the animation facility is also included in the package.
INTRODUCTION
Gear is a very common machine element in mechanical engineering applications. However, manufacturing of the gear seems to be fairly complicated even to the person having thorough technical knowledge in the related field. The conventional gear generation processes like forming, shaping, hobbing, etc. are usually represented in two-dimensional sketch. There may have some component that is not adequately described by the two-dimensional approach. In case of gear generation, it may be difficult to understand the complex geometries and the manufacturing arrangement with the help of 2D models. These limitations can be partially overcome and understanding will be more meaningful if one uses 3D solid model instead. However the development of the models using 3D solids may not always ensure the clarity of the complex gear generation process unless one uses animation to represent the motion of the gear blank and the gear cutter. This can be achieved very efficiently with the help of Virtual Manufacturing technique. It is a technology to create virtual environment on the computer screen to simulate the physical world. The knowledge base and expertise gained from the work in the virtual environment enables the user to apply them more meaningfully in the real life situation.
A host of literature is available on Virtual Manufacturing in different areas among which some of the recent and important works are referred below. Tesic and Banerjee [1] have worked in the area of rapid prototyping, which is a new technology for design, visualization and verification. Graphical user interfaces, Virtual Reality technologies,
distillation, segregation and auto interpretation are some of the important features of their work. Balyliss et. al [2] dealt with the development of models in a virtual environment using the virtual reality technologies providing an outstanding 3D visualization of the object. In 1994, G.M.Balyliss et. al [3] presented theoretic solid modeling techniques using the VM tools, like VRML (Virtual Reality Manufacturing Language) and 3D-STUDIO MAX. They have developed different parts of an automobile and through the special effect of animation imparted all possible motion to the model. The modeling technology is further enhanced by Kimera [4], who treated product and process modeling as a kernel for virtual manufacturing environment. In his work, Kimura has incorporated significant modeling issues like representation, representation language, abstraction, standardization, configuration control, etc. Arangarasan and Gadh [5] contributed towards the virtual prototyping that are constructed using simulation of the planned production process using virtual manufacturing on a platform of MAYA, 3D- STUIDO-MAX and VRML, etc. At Jadavpur University, research work [6] is carried out to simulate the gear manufacturing processes using AUTOCAD as the platform. A software has been developed that helps the design engineers to understand the problems related to spur gear operation and its manufacturing process.
A study of the state of the art and literature review reveal that the scope of virtual manufacturing is wide open for spur gear generation. Computer simulation can be very effectively used to view and subsequent analysis of different complicated manufacturing processes using the concept of design centered virtual manufacturing. With this objective in mind, an attempt is made to virtually manufacture a spur gear from the blank using a rack cutter. The scope of the work includes the generation of design data for the spur pinion and the rack form cutter, the generation of solid models for the cutter and blank and finally simulate gear-manufacturing process through animation.
The main motivation of the work is to simplify the task of designing and study the gear generation process that can be understood by a layman and to present a realistic view of it. All the processes are developed on the platform of the 3D-STUDIO-MAX, which is one of the most important virtual tools. The software is developed using Max-script, an object contained programming language that can be run in 3D-STUDIO-MAX environment.

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